U.S. Pat. No. 4,981,097 discloses a system for closing an oil leaking rupture from an oil holding tank disposed in an oil carrying vessel disposed in water. This system includes a pillow storage container which is fixedly secured to the vessel above a hole in the deck of the vessel which overlies the tank and communicates therewith. The container has a releasably disposed floor disposed in the hole above the tank. The container can be pressurized and releasably contains a plurality of oil absorbent pillows. When the tank is ruptured, the floor of the container is automatically opened and the pillows fall by gravity into the tank. On board means are provided to collect any pillows which escape through the rupture into the water surrounding the vessel.
Subsequent to the issuance of U.S. Pat. No. 4,981,097, applicant conducted a series of experiments with this system. Applicant discovered, much to his surprise, that the pillows described in this known system will not function efficiently unless, as explained below, these pillows, in addition to being oil adsorbent and impervious to water, must have a density heavier than oil and lighter than water.